Studies of corrosion inhibitors for zinc–manganese batteries: quinoline quaternary ammonium phenolates

Abstract

Three compounds, hydroxyethyl quinoline quaternary ammonium phenolate, hydroxyethyl quinoline quaternary ammonium para-methyl phenolate and hydroxyethyl quinoline quaternary ammonium para-nitro phenolate were synthesized and tested as corrosion inhibitors for zinc–manganese batteries. Such quaternary ammonium salts derived from heterocylic molecule containing N atoms possess a higher density electron cloud around the functional groups and provide a larger projective area. From the analysis of bi-directional polarization curves and the electrochemical impedance spectra of zinc electrode measured in 26% NH 4Cl solutions containing one of these compounds, we demonstrated that the first two compounds exhibit good inhibiting effects toward zinc corrosion as the result of adsorption on zinc surface at open-circuit conditions. These compounds desorb from the surface and will no longer hinder the dissolution of zinc once the zinc electrode is anodically polarized to certain extent. This property is desirable for corrosion inhibitor to be used in chemical batteries.